Digester strainer



1, 2 April 19, 1927. P- R. PANZL 6 5 373 DIGESTER STRAINER Filed April 19, 1926 I 7112877/607' Paul B. Paw/2L.

Patented Apr. 19, 1927.

UNITE- srarss r FFICE.

IPAUL R. PANZL, OF SHAWINIGAN FALLS, QUEBEC, CANADA.

DIGESTER STRAINER.

Application filed April 19, 1926, Serial No. 102,898, and in Canada December 14, 1925 This invention relates to an improved device for releasing gas and liquor. from a digester in which wood is being treated by chemicals to reduce the same to pulp for use in the paper and pulp industry.

In the process of reduction of wood to pulp it is necessary to release a certain amount of the liquid and gases from the digester during the cooking process in order to produce circulation and uniform temperature in the mass of material under treatment.

It has been customary in the past to provide means at or near the top of the digester to allow the escape of the liquor and gas above referred to by means of devices attached either to the cover or to the neck of the digester and projecting into the bore of the neck of the digester and which consisted essentially of apipe connection projecting into the bore of the digest-er neck and protected on the inside of the digester by a perforated metal hemisphere, cone, discshaped or pipe-like fitting, the object of the perforations being to prevent the chips and pulp from passing out of the digester. Furthermore previous forms of strainers have been connected to the subsequent cooling and recovery apparatus by means of pipe connections through a cover of the digester, thus requiring the said piping to be disconnected every time the digester was emptied and filled.

The object of this invention is to provide a type of strainer which is permanently connected with the subsequent cooling and recovery apparatus and is so constructed and positioned as to eliminate any possible obstruction while the digester is being filled with a fresh charge of materials. The permanent connection of this device to the subsequent piping results in a great saving of time and much less deterioration of pipe and fittings, thus making the operation of the digesters more expeditious and freer from the usual troubles and expense. While the accompanying drawing shows the application of this device to a type of digester used in the sulphite process in which the digester cover, lining, strainer and sleeve must all be bronze, or of other acid resisting material, it is evident that this type of strainer made of other suitable materials can be used on digesters of other construction and for other purposes than shown.

Referring to the drawings:

Figure 1 is a sectional elevation of the upper port-ion of a digester tank with my improved strainer attached thereto.

Fig. 2 is a plan view partly broken away and shown in sect-ion of my improved strainer for digesters.

Like numerals refer to like parts throughout the views of the drawings.

In the drawings, 5 is the upper portion of a digester tank. 6 is a sleeve inserted in the neck 7 of the digester and between said sleeve and the neck 7 is a cement packing 8. The sleeve 6 is provided with an annular flange 9 which forms a seat for an annular member 10 which is provided with an annular chamber 11 and with a plurality of series of rows 12, 13, and 14 of perforations 15 and constitutes a strainer. The perforations of each of said rows are preferably positioned in staggered relation to the perforations in the row or rows adjacent thereto. A pipe 16 provides an outlet orifice for the gas and liquor rel-eased during the cooking process in the digester. The strainer 10 is fastened to the sleeve 6 by cap bolts 10.

A cover 17 is clamped to the digester by bolts 18 and nuts 19, the bolts being pivoted at 20 to ears 21 on the neck of the digester. A bronze lining 22 is interposed between the cover 17 and the strainer ring 10 and the strainer ring 10 is positioned upon the upper end of the sleeve 6 which, in effect, forms a part of the digester. It will be noted that the inner diameter or bore of the strainer 10 is the same as that of the sleeve 6 so that it forms no obstruction to the material while it is being fed into the digester.

The application and operation of the improved strainer in connection with a digester is as follows :Assuming the cover 17 to have been detached from the digester, the next step is to fill the digester with chips of wood which enter the digester through the neck in large quantities and at high velocity. The strainer hereinbefore described having its bore equal in diameter to the bore of the sleeve 6, presents no obstruction whatever to the rapid filling of the digester with chips. After the required amount of chips and chemicals have been introduced into the digester, the cover 17 is bolted into place and steam is admitted at the bottom of the digester to increase the temperature and pressure to the desired amount for the reduction of the chips to pulp. During this: period ot reduction it is necessary to release a certain amount oi gas and liquid from the digester in order to produce a uniform temperature of the mass of material under treatment, and this release made possible by the improved strainer ring forming the subjeot-i'nzitter of this invention by the gas and liquids pnssin through the perforations 15 into the annular chamber 11 and outwardly through the outlet pipe 16.

I claim:

In combination, at digester tank, a cover eesem therefor and n etroiner interpouer l between said cover and the upper end surface of the digz ester tent; and. comprising an annular uuunher provided with on :innulnr chamber and with an outlet orifice from said chumher and hnvingz; :1 plurality ol? pertorzitmm; extending into said rhun'iher through the inner Willi (it mid annular men'lher the diznneter oi' the here of said strainer being; suhstuntiully the some us the diameter of the hore o]? that portion of the digester adjacent thereto.

In testimony whereof I have hereunto set my hand.

PAUL I. PANZL. 

